Minnesota's Long-Term Phosphorus Trial: Phase I.

Developing and understanding Best Management Practices (BMPs) for phosphorus (P) is critical to maintain optimal crop production capacity and minimize negative environmental risks.  Fertilizer recommendations are an integral component of those BMPs.  Fertilizer recommendations based on the Sufficiency philosophy or the Build and Maintain (B&M) philosophy have created wide differences in total P fertilizer applied.  In today’s high yield environment, there is concern that the Sufficiency approach will not adequately meet the needs of the crop and that B&M better supports a higher yield potential.  In Fall 2010, long-term P management trials were established at six sites across Minnesota with the ultimate objective of comparing crop response to the two P recommendation philosophies.  Phase I established over a four year period replicated plots with soil test P Interpretation Classes over a range of Low, Medium, High, and Very High at each site.  Phase II will further examine crop response to applied P fertilizer and the overall production level when in previously established soil test P Interpretation Classes.  Fall 2014 marks the end of Phase I and the beginning of Phase II.  During the Phase I period, grain yield response to increasing Interpretation Classes varied among sites and among the four years from no response to a significant yield increase.  Phosphorus removal in the grain increased with increasing Interpretation Classes, although the response varied among sites. This poster will illustrate yield production and P removal response to the various P fertilizer levels applied during the Phase I period at the six sites across Minnesota.